1. Field of the Invention
The present invention relates to an installation structure for a hydroelectric power generation apparatus that generates hydroelectric power with flowing water of sea or river.
2. Description of the Related Art
Electrical power generation using the energy of flowing water of sea or river generally presents a challenge as to where a hydroelectric power generation apparatus should be installed. If a hydroelectric power generation apparatus is installed on the surface of water flowing at a high velocity, the water surface on which it is installed may obstruct water transport of ships, etc. Accordingly, installation of a hydroelectric power generation apparatus is generally difficult. If a hydroelectric power generation apparatus is installed at the bottom of the water, flow velocity may be low or lots of mud may be present there, which is unfavorable to a hydroelectric power generation apparatus.
It is, therefore, appropriate to install a hydroelectric power generation apparatus in an undersea or other underwater location that does not obstruct water transport, has sufficient flow velocity and where there is little mud. An example of a conventional hydroelectric power generation apparatus installed in an undersea location is described in Japanese Patent Application No. H07-259064. Various types of hydroelectric power generation apparatus have also been proposed, as described in Japanese Patent Application Laid-Open Nos. H05-39773 and 2007-177797.
The hydroelectric power generation apparatus disclosed in Japanese Patent Application Laid-Open No. H07-259064 has a structure as shown in FIGS. 5 and 6. In an ocean current of stable flow velocity and direction, a buoyancy body B having a generator C and a pipe A facing the flow is moored at a predetermined depth by a mooring 9 and an anchor 10 attached to the prow-area. The buoyancy body B is such that the entire surface of the prow-area is defined as an inlet 1 and that a cross-section (which is perpendicular to the ocean current and in which a water turbine 6 is mounted) of substantially the middle of the pipe A connecting the inlet 1 and the outlet 2 of the prow-area has the shape of a circle reduced in area to one several dozenth of the area of the inlet 1.
Consequently, the flow velocity of the sea current in the place of the water turbine 6 is accelerated by several dozen times of the flow velocity of the sea current in the inlet 1, and great power capacity can be obtained by utilizing the energy of the sea current. The energy of the sea current flowing in the pipe A is then converted into electrical energy by the water turbine 6 and generator C, and this electrical energy is distributed to land by means of a sea bottom power transmission line.
To keep the buoyancy body B horizontal, one closest to a stern among air tanks 3 that are separate from one another in lengthwise, widthwise, and vertical directions, is adjusted to the amount of water it contains. In addition, rudders 4 are provided in upper and lower positions and left and right positions outside the stern, and the inlet 1 in the prow-area is oriented to face the sea current, thereby keeping the position of the buoyancy body B.
A hydroelectric power generation apparatus disclosed in Japanese Patent Application Laid-Open No. H07-259064 adjusts the amounts of water in the plurality of air tanks 3 in order to maintain the horizontal position of the buoyancy body B, and also has the rudders 4. However, if the buoyancy body B is small, this body B may easily be rotated or moved upward or downward or leftward or rightward by a water flow. It may therefore be difficult for the buoyancy body B to be kept horizontal. This requires an increase in the size of the buoyancy body B. Additionally, the integration of the generator C and the buoyancy body B contributes to such a problem as the size of a sea-current power generation submarine (i.e., hydroelectric power generation apparatus) increasing and the cost of each hydroelectric power generation apparatus correspondingly increasing excessively.
In order that the hydroelectric power generation apparatus be balanced relative to the water current, the inlet has to be formed in the shape of a streamer. This results in a very long tunnel-like tube A (i.e., channel) in the direction of water flow. Water may hardly flow into such a long tunnel-like pipe A.
A first object of the present invention is to provide an installation structure for a hydroelectric power generation apparatus that efficiently generates a large quantity of power without increasing the size of the hydroelectric power generation apparatus and that is economical.
A second object of the present invention is to provide an installation structure for a hydroelectric power generation apparatus, which makes it possible to install a plurality of hydroelectric power generation apparatuses such that hydroelectric power generation apparatuses with shorter channels are balanced perpendicular to water flow.
A third object of the present invention is to provide an installation structure for a hydroelectric power generation apparatus that excels in ease of maintenance.